Do babies have gills?

Question

My sister (who is a propagator of urban myths) used to claim that foetuses up to a certain stage of development breathe through gills, which then become stunted. Can anybody confirm or deny this with science?

Answer 1

No.

At a certain stage, the embryo has pharyngeal arches, the structure which develops into gills (and jaws) in fish. In humans it develops into the jaws and larynx. At one time (19th century) people thought that embryological development recapitulated phylogenetic development (evolution) but it isn't true. Strangely, it is often still repeated in biology texts.

The embryo always absorbs oxygen from its mother, via the umbilical cord. Neither gills no lungs are used for breathing before birth.

Stephen J. Gould wrote a couple of essays on this topic.

Answer 2

Foetuses do indeed have gills at a certain stage of development, but they do not use them to breathe. All sustenance comes from the mother.

Here's a reference for you:

Yes, we do form gills during foetal development. A 6 week old human foetus will have these "primitive gills" but by seven weeks they have disappeared, so it all happens very early in development (since human development can be
as long as 36 weeks).

The gills are called primitive gills because they do not actually develop to become real gills - they are always covered with skin.

I think you'll find, in P M's answer below, the meeting of the two theories rather than freaked out born-agains trying to slam evolution.

Answer 3

All vertebrate embryos develop gill arches. In all land animals however these are reabsorbed during development.

Placental mammal embryos get their oxygen through their umbilical chords. The gills don't function in the womb as they are absorbed long before they develop the needed anatomical developments that would make them even partially functional.

I doubt mammals could ever re-evolve gills as a primary breathing system our metabolisms are too fast for that methods inherent limitations. That's assuming aquatic parasites, bacteria and fungi wouldn't render the system too much of a liability.

I can't totally rule it out as a method for boosting submersion time as some sort of a secondary system, but sea mammals have been around for roughly 50 million years and it hasn't happened.

I'd guess that the embryonic gills are just briefly existing cartilaginous arches without all the plumbing needed for them to serve any real purpose. They'd need a pretty straight wide connection with the mouth and a lot of risky reworking of the circulatory system.

Answer 4

What? No human baby has gills. Maybe baby fishes have gills. Is your sister an expert on human anatomy? If so does she possess the credintials to back this claim up? Perhaps she's just a kid playing an evil prank on you?

Answer 5

It is rubbish. It is just that the embryonic human has gill pouches in it's neck, fish and amphibian embryos at the same stage also have these structures but they won't even have actual gills then either. The tissue that is equivalent goes on to contain the gills in these creatures later, but mammalian foetuses never go through a phase of having gills.

Answer 6

Well, to a certain point in a baby's fetus, we do posses gills, but they were never used. As a fetus, human babies will look similar to alot of animals and one of the similarity is gills, but then our genes kicks in the were lose the gills.

Answer 7

Oxygen comes to the fetus by way of the umbilical cord. Fetus' do not "breathe" and you can see this is not possible by the mucus plugs in our throat and nose when in utero. AND any medical professional, or you're mom for cryin' out loud, should be able to tell you that fetus' get nourishment and oxygen thru the umbilical cord and placenta, not gills (hahaha!). When the child is finally born, the nurse sucks the mucus out of the nose and throat, with a bulb syringe, so that the baby CAN take it's first real breath of air. THAT is why they want us to cry when were born, so they know we are finally breathing air.
Man, I thought my sister was mean when she told me her first "real" sister lived in a hole in the driveway. I stopped believing her when I realized the hole was too small (about two days...hey I was only 4 yrs old!) But, damn, you're old enough to post a Q! You're sister KNOWS who's picture is next to gullible in the dictionary! Must be that you're mom does too! How old are you?

Answer 8

Yes, in the early stages of development, the fetus has gills. They are not, however, used for breathing. One other tidbit, when they start out, a fetus also has a vestigial tail. Vestigial means it's a left over from times long past.

Answer 9

Actually, fetuses do develop gill structures and a tail in the first couple of weeks. However, they do not breathe through rthem.

The three inner bones of the human ear evolved from bones in fish that support their gills.

There is a famous saying in biology: "ontogeny recapitulates phylogeny." Check it out.

Answer 10

If a baby had gills, it would have it the entire way along.

The baby gets it's oxygen and food supply through the umbilical cord. The cord isn't just one big lump...it's full of sections bringing/taking things to and from the baby.